Any member of a clade of vascular plants (sometimes called Monilophyta) based on molecular genetic analysis, comprising the whisk ferns, horsetails, ferns, and their allies such as adders’ tongues (Ophioglossaceae), moonworts, and grape ferns. Like their sister clade, the seed plants, monilophytes have a differentiated main stem and side branches, but they reproduce by spores instead of seeds. See also euphyllophyte.